The invention relates to a process for the automatic regulation of the distance between a vehicle being regulated and another vehicle.
A process of this type is known from DE 44 37 678 A1 (incorporated herein by reference).
In the known process for the automatic regulation of distances, a distance-regulating device is provided in a vehicle which adjusts the distance to a preceding vehicle according to predetermined algorithms by automatically changing the speed of the vehicle to be regulated. The speed can be changed by the distance regulating device emitting actuating signals to the braking system or to the engine controls of the vehicle being regulated.
For distance regulation, the highest possible degree of regulation quality is desired, as in fact for all controls. This is understood to be the quickest possible compensation for regulating deviations with minimal overshooting.
It is therefore the object of the present invention to provide a process for automatic regulation of the distance between a vehicle being regulated and another vehicle by means of which a regulation quality that is an improvement over known processes can be attained through simple means.
In accordance with the present invention, a process is disclosed for the automatic regulation of the distance between a vehicle to be regulated and another vehicle. The vehicle to be regulated has a distance regulating device and a braking system which is actuable by the distance regulating device when the distance regulating device emits a brake actuation signal to the braking system. The inventive process comprises, prior to emitting the brake actuation signal, the distance regulating device emits a braking readiness signal to the braking system thereby causing the braking system to assume a braking readiness state. Once the braking system is in the braking readiness state, it takes less time than usual for the brakes to actuate after the distance regulating device emits a brake actuation signal.
It is an advantage of the invention that the effect of response lags of mechanical transmission elements in the braking system on the distance regulation are minimized. Thus, for example, the response lag of braking systems of conventional design, e.g., friction brakes, occurs due to the fact that when the brakes are actuated, the brake cylinders must first overcome a dead distance, also called venting clearance. Within the range of this dead distance, the vehicle is not braked. By using the present invention, a higher degree of regulation quality can be achieved than has previously been possible.
The invention has the further advantage that it is very economical because it can be realized through a simple adaptation of the control programs of the known distance regulating device and brake control system. Expensive optimization of the mechanical transmission elements of the engine controls or of the braking system in order to decrease dead times is not required.
It is another advantage of the invention that the regulation amplitudes, i.e., the magnitude of the changes in speed due to the actuation of the distance-regulating device, are reduced so that the regulating behavior is smoother, thus increasing traveling comfort. The reduction of the regulating amplitudes also results in a reduction of fuel consumption. In addition, the so-called xe2x80x9ccolumn stabilityxe2x80x9d of vehicles is considerably improved when the process according to the invention is used. Column stability in this context is understood to be the avoidance of surges in distance between a plurality of vehicles whose intervals are regulated automatically and which are traveling in a column.
In an advantageous further development of the invention, the distance-regulating device transmits the braking readiness signal to the braking system at a time when braking can be expected to occur shortly based on the xe2x80x9csurrounding conditions.xe2x80x9d Among the surrounding conditions which may trigger the braking readiness signal, the following are mentioned:
A vehicle in an adjoining traveling lane tends to encroach upon the travel lane of the vehicle to be regulated.
One or several vehicles in the adjoining lane to the left are decelerating or traveling at a lower speed than the vehicle to be regulated.
A preceding vehicle in the same lane decelerates slightly, so that an adaptation of the distance to the vehicle to be regulated is possible by reducing its engine performance without brake actuation.
A vehicle traveling in front of the preceding vehicle in the same lane decelerates.
A road condition ahead indicates that braking will be necessary, e.g., the vehicle to be regulated approaches a relatively tight curve in the road or a highway exit ramp. The road condition ahead can be determined here by using a road-map provided in a digital form, together with a device to determine vehicle coordinates, e.g., a GPS receiver (GPS=Global Positioning System).
In general, xe2x80x9csurrounding conditions where braking can be expected to occur shortlyxe2x80x9d is understood to be any traffic situation familiar to an experienced driver in which; he will be increasingly prepared to brake, such as in one or all of the above-mentioned cases or other situations.
Situations of the above-mentioned kind can also be recognized through an evaluation of optical signals, e.g., by means of an image recording device located in the vehicle to be regulated. Thus, a lane change by a vehicle in an adjoining lane can be recognized when its turn signal is actuated. A deceleration by a preceding vehicle can be recognized by detecting the brake light.